This invention relates generally to rotary friction couplings whereby an output shaft can be coupled for rotation with a rotating input shaft and, more particularly, to a rotary friction coupling having double conic friction surfaces which are selectively engageable to engage the coupling.
Rotary friction couplings having conic friction surfaces for coupling a rotary input shaft to an output shaft are known. For example, such couplings are utilized in drive transmissions for powering a ship's propeller.
Such rotary friction couplings generally comprise a fixed outer part and an inner part mounted for axial movement within the outer part in order to effect engagement and disengagement of the coupling. Such axial movement of the inner part is generally accomplished by means of a gear and associated annular wheel or, alternatively, by means of a plurality of keys slidably located within associated slots. Neither of these arrangements allow or provide for any angular deviation of the shaft from the axis during operation of the coupling. However, since some angular deviations always exist due, for example, to imperfect installation, loading during operation, etc., the inflexible nature of the slidable interconnection between the inner part and outer part often results in undue wear of the slide arrangement of the inner part. Such wear produces metal particles which often get caught in the coupling causing the same to jam as well as producing other kinds of troubles.
Conventional rotary couplings having conic friction surfaces must be manufactured and installed in a manner such that a high degree of concentricity is maintained between the inner and outer parts of the coupling. Thus, it is recognized that even a slight degree of eccentricity between the outer and inner parts will result in losses in the capacity of the coupling to transmit torque.
It is also known that conventional rotary couplings of the type described above operate in less than a satisfactory manner when positioned in a vertical orientation.